Many different types of alignment devices, such as straightedge and squaring devices are known. One common alignment device is a carpenter's square. The carpenter's square, also referred to as a flat square, a rafter square, a builder's square, a roofing square, etc. may have a variety of uses. Typically, carpenter's squares are L-shaped and may be used for measuring and marking patterns in framing, roofing, and stairway work. The carpenter's square also may be used as a straightedge for determining the flatness of a surface.
Such carpenter's squares may be used to ensure that a line or cut is square or plumb. For example, the L-shape of most carpenter's squares enables users to determine whether a line or cut is perpendicular from a reference surface, such as an edge of a plank. Such a determination may be made by resting a first portion of the square against the reference surface and aligning a second perpendicular portion, or leg, of the square with the line or cut. The user then may compare the position of the leg with the selected line or cut and thereby determine whether such a line or cut is square.
Additionally, some carpenter's squares enable a user to check angles of 30, 45, and 60 degrees. However, the uses of such carpenter's squares may be limited to measuring and checking the preformed angles of the alignment device. Thus, an alignment device having a 90-degree edge may be used for checking and marking 90-degree angles. Similarly, an alignment device with a 45-degree edge may be used for checking and marking 45-degree angles. However, it may be difficult to use the alignment device having a 90-degree or 45-degree edge to check and mark a 60-degree angle. Thus, versatility of such an alignment device may be limited.
Carpenter's squares further may be used to measure and mark a desired cutting line. For example, when a user wants to cut the plank with a handheld cutting device, such as a circular saw, the user may measure and mark a point on a plank where the plank is to be cut. The user may use a carpenter's square or other straightedge device to guide a marking instrument, such as a pencil or pen, from the measured point along the desired cutting line, thereby creating a marked line on the surface of the plank. After marking a desired cutting line, a user may align the blade of the saw with the marked line, and move the saw in such a manner as to ensure that the blade follows the path of the drawn line. Various conditions, such as the type of wood, weather conditions, such as rain, or byproducts from cutting, e.g. sawdust, may erase or obscure the marked line from the user making it difficult, if not impossible, for the user to accurately cut the plank. Additionally, the shape of the cutting device may prevent a user from accurately sighting the marked line while cutting. Moreover, inexperienced users may find it difficult to follow the marked line with the cutting device, and thus, although the line may have been straight, the cut, itself, may not.